Pain Signalling Group, Neuropharmacology and Neurobiology Section, School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
Brain Behav Immun. 2010 May;24(4):569-76. doi: 10.1016/j.bbi.2009.12.007. Epub 2009 Dec 24.
Spinal release of cytokines may play a critical role in the maladapted nociceptive signaling underlying chronic pain states. In order to investigate this biology, we have developed a novel 'high flux' intrathecal microdialysis approach in combination with multiplex bead-based immunoassay technology to concurrently monitor the spinal release of interleukin (IL)-1beta, IL-6 and tumour necrosis factor (TNF)alpha in rats with unilateral sciatic nerve chronic constriction injury (CCI). Intrathecal microdialysis was performed under isoflurane/N(2)O anaesthesia in rats with confirmed mechanical hypersensitivity. In a first study, C-fiber strength electrical stimulation of the operated nerve in neuropathic rats was found to evoke a dramatic increase in IL-1beta efflux ( approximately 15-fold) that was significantly greater than that observed in the sham-operated group. Spinal IL-6 efflux was also responsive to primary afferent stimulation, whereas TNFalpha was not. In a second study, treatment with the glial inhibitor propentofylline for 7days normalized CCI-induced mechanical hypersensitivity. In the same animals, this treatment also significantly reduced intrathecal IL-1beta, IL-6 and TNFalpha and prevented afferent stimulation-evoked cytokine release of both IL-1beta and IL-6. These results provide support for glia as the source of the majority of intrathecal IL-1beta, IL-6 and TNFalpha that accompanies mechanical hypersensitivity in the CCI rat. Moreover, our studies demonstrate the ability of a neurone-glia signaling mechanism to dynamically modulate this release and support a role of spinal IL-1beta in the phasic transmission of abnormal pain signals.
细胞因子的脊髓释放可能在慢性疼痛状态下适应性疼痛信号传导异常中发挥关键作用。为了研究这种生物学机制，我们开发了一种新型的“高通量”鞘内微透析方法，并结合基于多色微珠的免疫分析技术，以同时监测慢性坐骨神经缩窄性损伤（CCI）大鼠的脊髓中白细胞介素（IL）-1β、IL-6 和肿瘤坏死因子（TNF）α的释放。在确认存在机械性超敏反应的大鼠中，在异氟烷/N₂O 麻醉下进行鞘内微透析。在第一项研究中，发现对神经病理性大鼠手术神经的 C 纤维强度电刺激会引起 IL-1β流出的剧烈增加（约增加 15 倍），这明显大于 sham 手术组观察到的增加。脊髓 IL-6 流出也对初级传入刺激有反应，而 TNFα则没有。在第二项研究中，用神经胶质抑制剂丙戊茶碱治疗 7 天可使 CCI 诱导的机械性超敏正常化。在相同的动物中，这种治疗还显著降低了鞘内 IL-1β、IL-6 和 TNFα，并防止了传入刺激诱发的 IL-1β和 IL-6 的细胞因子释放。这些结果为胶质细胞是伴随 CCI 大鼠机械性超敏的鞘内 IL-1β、IL-6 和 TNFα的主要来源提供了支持。此外，我们的研究表明神经元-胶质信号机制有能力动态调节这种释放，并支持脊髓 IL-1β在异常疼痛信号的相位传递中的作用。
